AIX Version 4.3 Differences Guide

already available than it is to create a new kernel thread once the event
has taken place.
AIXTHREAD_MINKTHREADS
This variable is a manual override to the AIXTHREAD_MNRATIO. It
allows you to stipulate the minimum number of active kernel threads.
The library scheduler will not reclaim kernel threads below this number.
SPINLOOPTIME
This variable controls the number of times the system will try to get a
busy lock without taking a secondary action, such as calling the kernel
to yield the processor. This control is really intended for MP systems
where it is hoped that the lock is held by another actively running
pthread and will soon be released. On uniprocessor systems, this value
is ignored.
YIELDLOOPTIME
This variable controls the number of times that the system yields the
processor when trying to acquire a busy mutex or spin lock before
actually going to sleep on the lock. This variable has been shown to be
effective in complex applications where multiple locks are in use.
4.3.6 Maximum Number of Threads
The maximum number of threads a single process can create has been increased
to 32767. To obtain this limit, it is necessary to increase the data limit for the
process since stacks are malloced out of the heap. If may also be necessary to
use the large program model.
4.3.7 Combined Thread-Safe Libraries
Non-thread-safe and thread-safe libraries have been combined into one set of
libraries, thereby turning thread-safety on by default.
AIX Version 4.2 libc.a (non-thread-safe) and libc_r.a (thread-safe).
AIX Version 4.3.1 libc.a which is thread-safe.
Libraries, such as X11R6, which link with libc.a are not thread-safe by default;
they are thread-aware.
New libraries that are thread-safe include:
• libbsd.a
• libm.a
• libmsaa.a
• librts.a
• libodm.a
• libs.a
• libdes.a
• libXm.a
• libXt.a
• libX11.a
These thread-safe libraries enable a convenient programming model for
exploiting SMPs and simplify exploitation of threads by applications, middleware,
and other API providers.
Application Development and Pthreads 75